Howling noise from fuel vent

[maxargonaut]

After lots of head scratching and three failed attempts by a local Porsche garage to diagnose this, I took it to a dealer and they replaced the "Fuel Tank Vent Valve" and valve housing and the problem went away. I was also having trouble filling the tank all the way (it would shut off after 3/4 of the tank or so, after which I had to baby the gas in until the tank was full). This took care of that too.

I tried the "put some sponge in the hole" fix, but (a) it made filling the tank impossible unless I took the sponge out first, and (b) under heavy accelleration the car hitched like it was running out of gas. I only ran into that latter problem once before I decided to live with the noise instead.

This fix cost me $800, but it's a great relief to have it taken care of finally.